There have been conventionally studied surface treatment methods such as metal coating, nonmetal coating, and chemical conversion coating. So far, various functional composite materials have been created using a matrix of a metal provided on a surface thereof with a film of another metal.
Plating is one of typical examples of the several surface treatment methods. This plating technique is utilized also in the magnetic recording technology, for example. Specifically, there is disclosed a technique of filling up a large number of pores formed in a surface layer of a matrix of alumina (Al2O3) with cobalt by alternate plating (Non-Patent Document 1, for example). Possibly, this technique will be significantly important in the production of high density magnetic recording media. However, in this technique, there arise problems such as limited decrease in cost in the entire equipment due to necessity of an alternating current power supply and the like. There is also disclosed a technique of forming a porous layer with use of a special substrate and filling up pores in the porous layer with a plating material by displacement plating (Patent Document 1). However, this technique adopting the substrate in a special structure definitely requires the complex production steps and increase in production cost therefor.
Silicon, which is most widely used in the fields of semiconductor, MEMS, and the like, can be a preferable material as a matrix of a magnetic recording medium because of its capability of stable supply. There has been actually proposed a magnetic recording medium using a silicon matrix (Patent Document 2, for example). For example, if developments are made in a technique of plating a silicon surface layer provided with non-penetrating pores with a high degree of accuracy, in other words, so as to leave voids as less as possible, such a technique will be an important element for production of high density magnetic recording media.    Non-Patent Document 1: K. Ito and one other, “Nanohole Patterned Media”, Journal FUJITSU, Fujitsu Limited, January 2007, Vol. 58, No. 1, pp. 90-98    Non-Patent Document 2: S. Yae and four others, “Electrochemistry Communications”, August 2003, Vol. 5, p. 632    Non-Patent Document 3: K. Tsujino and one other, “Electrochemica Acta”, Nov. 20, 2007, Vol. 53, p. 28    Patent Document 1: Japanese Unexamined Patent Publication No. 2006-342402    Patent Document 2: Japanese Unexamined Patent Publication No. S57-105826    Patent Document 3: Japanese Unexamined Patent Publication No. H11-283829    Patent Document 4: Japanese Unexamined Patent Publication No. 2003-288712    Patent Document 5: Japanese Unexamined Patent Publication No. 2004-237429    Patent Document 6: Japanese Unexamined Patent Publication No. 2005-139376    Patent Document 7: Japanese Unexamined Patent Publication No. 2007-533983    Patent Document 8: United States Unexamined Patent Publication No. 2005/0101153